SAGE III Ozone Loss and Validation Experiment (SOLVE)

September 1999 - March 2000

The SAGE III Ozone Loss and Validation Experiment (SOLVE) is a measurement campaign designed to examine the processes controlling ozone levels at mid- to high latitudes. Measurements will be made in the Arctic high-latitude region in winter using the NASA DC-8 and ER-2 aircraft, as well as balloon platforms and ground-based instruments. The mission will also acquire correlative data needed to validate the Stratospheric Aerosol and Gas Experiment (SAGE) III satellite measurements that will be used to quantitatively assess high-latitude ozone loss. SOLVE is co-sponsored by the Upper Atmosphere Research Program (UARP), Atmospheric Effects of Aviation Project (AEAP), Atmospheric Chemistry Modeling and Analysis Program (ACMAP), and Earth Observing System (EOS) of NASA's Earth Science Enterprise (ESE) as part of the validation program for the SAGE III instrument.

CSD (formerly the Aeronomy Laboratory) Participation in SOLVE:

Measurement of reactive nitrogen (NOy)

Reactive nitrogen (NOy = NO + NO2 + NO3 + 2N2O5 + HONO + HO2NO2 + HNO3 + PAN + ClONO2 + aerosol nitrate + ...) plays an integral role in the photochemistry, heterogeneous chemistry, and ozone destruction cycles of the upper troposphere and lower stratosphere. During SOLVE, members of the Aeronomy Laboratory will measure both NO and NOy with a multi-channel chemiluminescence detector on the ER-2 platform.

Ozone destruction by anthropogenic chlorine compounds is believed to be enhanced through heterogeneous reactions that occur on Polar Stratospheric Clouds (PSCs) in the polar regions. A major objective of the NOy group for the SOLVE mission is to augment the limited number of in situ PSC observations in the Arctic. These observations are expected to provide further insight into the composition and formation mechanism of PSCs. In addition, evidence from previous Arctic missions suggests that the fallout of reactive nitrogen from the stratosphere (denitrification) perpetuates the ozone destruction cycle. Measurements of NOy taken in denitrified air during SOLVE should help diagnose the mechanisms of denitrification in the Arctic stratosphere. Lastly, measurements of NOy coupled with the host of other species measured on the ER-2 will help to complete the picture of photochemical partitioning in the Arctic stratosphere.

Analysis of mesoscale processes using campaign data

One of the principal objectives of SOLVE is to understand the processes controlling ozone levels at middle and high latitudes. The relative importance of the roles played by chemistry and dynamics is not clearly defined. In particular, many modeling studies have failed to satisfactorily account for northern hemisphere polar and mid-latitude ozone trends over the past several decades.

One process responsible for the redistribution of ozone in the lower stratosphere is the formation and advection of thin layers of ozone-rich and ozone-poor air, known as ozone laminae. Laminae are extremely abundant in the vicinity of the polar vortex boundary, but there have never been adequate observations to properly identify the importance of this process as a means of transporting vortex air into mid-latitudes.

The extensive data sets which will arise from the SOLVE campaign are expected to afford an opportunity to address issues related to transport on small vertical scales. The co-location of measurements from a number of different platforms is expected to provide, for the first time, simultaneous observations of laminae in two dimensions. Measurements of trace species, plus pressure and temperature profiles, from the SAGE III satellite will provide valuable supplementary information in the regions where the NASA aircraft fly, as well as at other locations along the vortex boundary, with a view to identifying the principal source regions for laminae.